Sport is very important for young people. Although some guys do not get enough sport. From my point of view, I think practising any sport is importat to maturing process and practice can help teenagers to learn the importance of the discipline, perseverance and effort.
Hence, I think it encourages competitiveness, but always with moderation not too much insistence . So boys or girls will learn to enjoy the victories and become stronger with defeats.
Furthermore, If you take up a team sport, you will meet new people, new friends.
In fact most teenagers play sports like football or basketball, but personally it doesn’t matter.
For example my little brother does fencing, it’s not a usual sport and when you don’t know about it, you don't think that someone could practices this sport, but in fact there are a lot of boys and girls who practice it.